Super-stretchy gel could replace damaged cartilage

时间：2019-03-02 06:04:04166网络整理admin

By Phil McKenna A flexible but resilient gel that could be used as artificial cartilage to repair ailing joints is being investigated by US researchers. Made from polymers commonly found in shampoo, the water-based gel could help people with joint diseases like arthritis – a disease affecting 46 million people in the US alone. “You can squeeze it or pull it by 10 times its original length and it still won’t fall apart,” says Eric Lin of the US National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, US. “If you tried to do that with Jell-O [jelly] or any other material that was 90% water it would just fall apart.” Natural cartilage has comparable strength. Its gel mimic – first created in 2003 by researchers at Hokkaido University, Japan – is made by mixing two polymers with water in a specific ratio. By blasting the gel with neutrons to reveal its atomic structure, Lin and colleagues have now uncovered precisely what happens to it when stressed. They found the two polymers form strong integrated bonds at regular intervals across the compound. But when the gel is deformed, those bonds can temporarily break apart to release tension before reforming. “Instead of one big crack, its like tens of thousands of small micro-cracks that work like mini shock absorbers at every micron along the material,” say Wen-li Wu, also of NIST. The researchers say the understanding of how the material holds together under stress will help guide the design of an artificial cartilage material. One alternative to the artificial approach, though, is to grow a patient extra cartilage in the lab using a few cells taken from one of their own joints. Anthony Hollander of Bristol University, UK, was the first to prove that lab-grown cartilage can benefit patients, but concedes that artificial cartilage has its benefits. “The great advantage of their approach, if it really works, is it’s an off-the-shelf technique,” Hollander says. “Growing the patients’ own cells in an ultra-clean lab is expensive.” Still, Hollander says cartilage is highly complex tissue that may be hard to replace. He adds that if artificial cartilage is implanted to fill a gap of missing tissue, it would likely result in pressure points where it brushes up against existing cartilage. “My guess is for the most challenging patients we will need a laboratory engineered, natural tissue,” Hollander says. A paper on the artificial cartilage was presented at the American Physical Society meeting in New Orleans,